Class 11 - Computer || Chapter 2 || Classification of Computers

 CHAPTER 2
CLASSIFICATION OF COMPUTERS

Classification of Computers on the basis of Technology  

The computers can be classified based on the technology being used as: Digital, Analog and Hybrid 

Digital Computers

These computers are capable of processing information in discrete form. In digital  technology data which can be in the form of letters, symbols or numbers is represented in binary form i.e. 0s and 1s. Binary digits are easily expressed in a digital computer by the presence (1) or absence (0) of current or voltage. It computes by counting and adding operations. The digital computers are used in industrial, business and scientific applications. They are quite suitable for large volume data processing.

Analog Computers

An analog computer works on continuously changeable aspects of physical phenomenon such as fluid pressure, mechanical motion and electrical quantities. These computers measure changes in continuous physical quantities say current and voltage. These computers are used to process data generated by ongoing physical processes. A thermometer is an example of an analog computer since it measures the change in mercury level continuously. Although the accuracy of an analog computer is less as compared to digital computers, yet it is used to process data generated by changing physical quantities especially when the response to change is fast. Most present day analog computers are well suited to simulating systems. A simulator helps to conduct experiments repeatedly in real time environment. Some of the common examples are simulations in aircrafts, nuclear power plants, hydraulic and electronic networks. 

Differences Between Analog and Digital Signals:

Analog	Digital
Analog signal is a continuous signal which represents physical measurements.	Digital signals are discrete time signals generated by digital modulation.
Denoted by sine waves	Denoted by square waves
Uses continuous range of values to represent information	Uses discrete or discontinuous values to represent information
Subjected to deterioration by noise during transmission and write/read cycle.	Can be noise-immune without deterioration during transmission and write/read cycle.
Analog instrument draws large power	Digital instrument draws only negligible power
Low cost and portable	Cost is high and not easily portable

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Hybrid Computers 

These use both analog and digital technology. It has the speed of analog computer and the accuracy of a digital computer. It may accept digital or analog signals but an extensive conversion of data from digital to analog and analog to digital has to be done. Generally the analog components provide efficient processing of differential equations while the digital part deals with logical operations of the system. Hence benefits of both analog and digital computing are readily available. Hybrid Computers are used as a cost effective means for complex simulations. 

Classification of Digital Computers 

The digital computers are classified according to their computing capabilities. The various types of digital computers are discussed below: 

Micro Computers

These are also known as Personal Computers. These type of digital computer uses a microprocessor (a CPU on a single chip) and include both desktops and laptops. These computers can work on small volume of data, are very versatile and can handle varieties of applications. These computers are being used as work stations, CAD, multimedia and advertising applications. Small portable computers such as PDAs (Personal Digital Assistants) and tablets with wireless computing technology are increasingly becoming popular.

Mini Computers 

These computers can support multiple users working simultaneously on the same machine. These are mainly used in an organization where computers installed in various departments are interconnected. These computers are useful for small business organizations. 

Main Frames

These computers are large and very powerful computers with very high memory capacity. These can process huge databases such as census at extremely fast rate. They are suitable for big organizations, banks, industries etc. and can support hundreds of users simultaneously on the network.

 

Super Computers

These are fastest and very expensive computers. They can execute billions of instructions per second. These are multiprocessor, parallel systems suitable for specialized complex scientific applications involving huge amounts of mathematical applications such as weather forecasting. The main difference between a supercomputer and a mainframe is that a supercomputer executes fewer programs as fast as possible whereas a mainframe executes many programs concurrently.

Classification of Computers on the basis of Brand

On the basis of brand , the computer can be classified as IBM PC, IBM compatibles and Apple/Macintosh computer.

IBM PC: 

IBM PC is the largest computer manufacturing company establishing USA. The computer manufactures by IBM PC or branded computer. Personal Computer (PC) is the most important type of micro computer system. The micro computer manufactures by IBM Company are called IBM PC. These computers are reliable, durable and have better quality but they are costly.

IBM Compatibles: 

The computers that have some functional characteristics and principles of IBM computer are called IBM compatibles. In other word, all the computer are manufactured by the another companies rather than IBM company are Known as IBM compatibles. All the software and hardware of IBM compatibles. These are cheaper and Their Parts are easily available in Market. They are also duplicate or assemble computer.

Apple/Macintosh Computer: 

All the computers manufacture by apple cooperation, a leading computers manufacturing computer of USA are known as Apple/Macintosh computers. These computers use their own software and hardware. They are totally different than that of IBM computers, In terms of both hardware and software. For e.g software developed for apple computer can't run or IBM computers and vice-versa. Similarly, floppy disk formatting in IBM computer can't be recognized by apple Macintosh computer and vice-versa. It are popularly used in desktop publishing (DTP) houses as they provide better quality of graphic output.

Classification of Computers on the basis of Model

On the basis of model computer is classified as:

XT (Extended / Extra Technology) Computer :

The computers that use 8086, 8088 microprocessor are called XT computers. The time periods for this computer are from 1975 - 1982. XT computers have processing speed of 4.77 MHz and are comparatively slow in speed. These processors are of 4, 8 or 16 bits of word length.

AT (Advanced Technology) Computer: 

With the development of 80286 microprocessor AT computer were introduced in the field of computers. The processors are of 8, 16, 32 or 64 bits of word length. The computers using Pentium I, Pentium pro & Pentium II are the examples of AT computers. The time periods for these computers are from 1982 - 1995. These computers can run any type of soft wares including text based as well as graphical base and processor speed of these computers is up to 233 MHz.

PS/2 (Personal System / 2) Computer: 

IBM started manufacturing next model of computer since 1990. This model is called PS? 2 computers. Most of the computers manufactured after 1990 including laptop, belongs to this model. These computers are refinement of AT computers. These computers can run almost all software & programs.